Span Calculator
Maximum allowable span for joists, rafters, and headers via bending + deflection check.
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Timber Construction Calculator
Span tables, insulation R/U-value, material quantity, plus rafter, stairs, and footings — based on KS standards and Korean building code.
Structural · Insulation · Quantity (Core)
Roof · Stairs · Foundation
Stair Calculator
Compute number of steps, riser height, and tread depth per Korean building code.
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Rafter Calculator
Compute rafter cut length, angle, and slope from run and rise.
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Roof Pitch Converter
Convert between angle, slope (%), and pitch (rise/12) representations.
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Roof Area
Plan area + slope angle → actual roof slope area + eave area.
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Concrete Volume
Strip footing or mat slab concrete volume + rebar weight + remicon truck count.
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Lumber Conversion
Convert lumber dimensions and count into volume, board feet, sai, and weight.
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Material & Finish Quantities
Quantity take-off calculators for brick, rebar, tile, wallpaper and other materials — useful for remodeling and interior estimates as well as timber framing.
Use the timber calculators in construction order
For foundations, the concrete and gravel calculators give pour volume and aggregate quantities. For framing, the stud, span, rafter, and roof pitch calculators size members and count quantities. Exterior work is covered by the roof area and siding calculators, interior work by insulation, drywall, plywood/OSB, and paint — with deck and stair tools completing the sequence.
Three principles apply to every takeoff: measure actual site dimensions rather than trusting drawings, add a waste factor that differs by material, and round up to purchasable units such as 4×8 sheets. The items most often missing from estimates are waste factors and consumables like nails, screws, and waterproofing membrane, so carry the margins shown in each result.
Structural calculators such as span and rafter reference light-frame construction tables, but actual construction must include a structural review for the loads involved. These tools support estimating and material ordering — they do not replace a structural engineer's judgment.